Cisco 7600 Series Router Software Configuration Guide, Cisco IOS Release 15S

ISSU Overview

Cisco IOS Releases 12.2SRB1 and later support ISSU on Cisco 7600 series routers. During an ISSU upgrade, the router continues to route and forward traffic, which allows you to upgrade from one software release to another with minimal system downtime (between 0 and 3 seconds).

ISSU is available for NSF/SSO compliant protocols and software features on the router. See the “ISSU Support” section for a list of Cisco 7600 protocols and features that support ISSU.

Note To perform an ISSU upgrade, the old and new Cisco IOS software releases must have the same line card software. If the releases have different line card software, the router performs an eFSU upgrade.

eFSU Overview

eFSU helps to minimize outage time during an in service software upgrade by preloading a new software image onto line cards that support the feature. During the software upgrade process, a switchover occurs between the active and standby supervisor engines or RSPs. When the switchover occurs, the line cards are restarted. Line cards that support eFSU are restarted with the new, preloaded software image.

The following Cisco 7600 line cards support eFSU:

• SIP-400 and SIP-600
• ESM-2x10GE and ESM-20x1GE-3C
• 67 xx line cards

All other Cisco 7600 line cards undergo a hard reset at switchover, and the software image is loaded after the line card is restarted.

Note To support eFSU, a line card must have 512 MB of memory, with enough memory available to hold the new software image. If enough memory is not available, the software preload fails and the line card undergoes a reset during the switchover.

Outage Time and Support Considerations

During an eFSU upgrade, line cards are restarted or reset after the switchover that occurs between processors. Because the line cards are restarted or reset, any links attached to the line cards flap and traffic processing is disrupted until protocols and software features are brought back online. The length of time that line card processing is disrupted (outage time) depends on whether the eFSU process was able to preload a new software image onto the line card.

• For line cards that support eFSU, the outage time is similar to that in RPR+ mode.
• For line cards that do not support eFSU, the outage time is similar to that in RPR mode.

Once the new software is downloaded (issu loadversion), you can use the show issu outage slot all command to display the maximum outage time for installed line cards. See the “Displaying Maximum Outage Time for Installed Line Cards (Optional)” section for a command example.

If you attempt to load an earlier version of software onto the router and the new (earlier) version does not support a currently installed line card, one of two things happens:

• If you use the force option in the issu loadversion command, the router is placed in RPR mode.
• If you omit the force option, the eFSU process is aborted and error messages are displayed to indicate that there is a problem with the line card.

Reserving Line Card Memory

On line cards that support eFSU, the router automatically reserves memory on the line card to store the new software image (decompressed format). The amount of memory needed varies according to line card type.

Although we do not recommend it, you can issue the following command to keep the router from reserving memory for the software preload (where slot-num specifies which slot the line card is installed in):

Note If a line card does not have enough memory available to hold the new software image, software preload fails and the card undergoes a reset during the switchover. Outage time is similar to that with RPR (because the new line card image must be loaded after the line card is restarted).

To determine how much memory will be reserved on the line card, use the show mdr download image command, as shown in the following example (for a Cisco 7600 SIP-600):

eFSU Operation

During a software upgrade, the router performs the following steps on line cards that support eFSU. These steps occur automatically during the upgrade process, and no user intervention is required.

• Reserves the necessary memory for the new Cisco IOS software image on each installed line card (if the line card supports software preload).
• Preloads a new software image onto supported line cards as part of the issu loadversion command.
• Restarts line cards with the new software image when switchover occurs (issu runversion).
• If a rollback or abort occurs, the router restores the line card software to its original version. To provide as little disruption as possible, the router preloads the original software version back onto the line card. Once the rollback or abort is completed, the line card is restarted with the original software version.

Error Handling for Line Card Software Preload

If problems occur during line card software preload, the router takes the following actions:

• Line card crash during load version—The line card is reset when switchover occurs.
• Line card not active when eFSU started—No power is provided to the line card during the software upgrade, and the line card is reset when the process ends. The same action is applied to a line card that is inserted into the router after the software upgrade process has begun.
• Line card crash during run version or during rollback—The line card boots with the software image version that corresponds to the software image that is present on the active supervisor engine or RSP.

ISSU Support

ISSU is supported on the following Cisco 7600 hardware and software:

Availability

• Cisco IOS Release 12.2SRB1 and later

Hardware

• All supported Cisco 7600 chassis (including enhanced [-S] chassis)
• RSP720-3C, RSP720-3CXL, Sup720-3B, Sup720-3BXL, Sup32
• All Cisco 7600 line cards, DFCs, and other modules

Software

• 802.1q
• 802.1x
• ARP
• ATM
• BGP
• Etherchannel (PagP and LACP)
• GLBP
• HDLC
• HSRP
• IPv4
• L2 multicast
• MLP (Multilink PPP)
• MPLS (including LDP, TE, and VPN)—See the ISSU MPLS Client document for information about the steps you should perform during the upgrade.
  http://www.cisco.com/en/US/docs/ios/mpls/configuration/guide/mp_issu_clients_ps6922_TSD_Products_Configuration_Guide_Chapter.html#wp1054109
• NetFlow
• PPP
• QoS
• RIB (routing information base)
• SNMP
• SPAN and Remote SPAN
• STP
• VRF (Virtual Routing and Forwarding)

ISSU Compatibility Matrix for Cisco IOS Software Releases

The following table lists the compatibility matrix for ISSU between various Cisco IOS releases for C7600. If the ISSU is supported between two releases the column is marked as yes and if ISSU is not supported between two releases the corresponding column is marked as no.

Table 6-1 ISSU Compatibility Matrix

eFSU Support

eFSU is supported on the following Cisco 7600 hardware and software:

Availability

• Cisco IOS Release 12.2SRB and later
• RSP720 and Sup32 support introduced in Release 12.2(33)SRB1

Hardware

• All Cisco 7600 chassis (except the 3-slot chassis, CISCO7603)
• RSP720-3C, RSP720-3CXL, Sup720-3B, Sup720-3BXL, Sup32
• DFC3B, DFC3BXL, DFC3C, DFC3CXL
• ESM-2x10GE, ESM-20x1GE-3C
• SIP-400, SIP-600, 67 xx line cards

Unsupported Hardware

• Enhanced FlexWAN, OSM-GE-WAN
• 68 xx, 65 xx, 64 xx, 63 xx, and 61 xx line cards

Software Support

During an eFSU, Cisco 7600 line cards are restarted, and software features and routing protocols are not available during the restart. Outage time depends on whether the line cards support eFSU (see the “eFSU Overview” section).

Software Upgrade Process Summary

Here is a summary of the tasks required to upgrade (or downgrade) a software image on the Cisco 7600 router. The following sections provide examples of the software upgrade process on the router.

The same set of ISSU commands and upgrade procedure are used for both ISSU and eFSU.

Note The ISSU upgrade process is available only for Cisco IOS releases that share the same line card software. If the line card software in the releases is different, the router performs an eFSU upgrade.

	Command or Action	Purpose
Step 1	Router> enable	Enables privileged EXEC mode. Enter your password if prompted.
Step 2	Router# copy tftp disk_name	Uses TFTP to copy the new software image to flash memory on the active and standby RPs (disk0: and slavedisk0:). Answer the prompts to identify the name and location of the new software image.
Step 3	Router# configure terminal	Enters global configuration mode.
Step 4	Router(config)# no service image-version efsu Router(config)# end	Disables the compatibility matrix check, which is necessary to perform a software upgrade on the Cisco 7600 router. The end command returns you to privileged EXEC mode.
Step 5	Router# show version | in image Router# show bootvar     Router# show redundancy Router# show issu state [ detail ]	These show commands verify that the router is ready to run ISSU or eFSU. The show version and show bootvar commands verify the boot image settings. The show redundancy and show issu state commands verify that redundancy mode is enabled and that SSO and NSF are configured. Note Use show redundancy and show issu state throughout the upgrade (as shown in the following examples) to verify the status of the upgrade.
Step 6	Router# issu loadversion active-slot active-image standby-slot standby-image [ force ]	Starts the upgrade process and loads the new software image onto the standby RP. It may take several seconds for the new image to load and for the standby RP to transition to SSO mode.
Step 7	Router# remote command switch show issu outage slot all	(Optional) Displays the maximum outage time for installed line cards. Issue the command on the switch processor (SP) of the supervisor engine or RSP. Note The command show issu outage slot all is supported on SP only.
Step 8	Router# issu runversion slot image	Forces a switchover, causing the standby supervisor engine or RSP to become active and begin running the new software. The previously active processor becomes standby and boots with the old image.
Step 9	Router# issu acceptversion { active slot-number | active slot-name slot-name }	(Optional) Halts the rollback timer to ensure that the new software image is not automatically aborted during the upgrade process.
Step 10	Router# issu commitversion slot active-image	Loads the new software image onto the standby supervisor engine or RSP in the specified slot.
Step 11	Router# show redundancy Router# show issu state [ detail ]	Verifies the status of the upgrade process. If the upgrade was successful, both the active and standby supervisor engines or RSPs are running the new software version.

Preparing for the Upgrade

Before attempting to perform a software upgrade, be sure to review the “Cisco 7600 ISSU and eFSU Guidelines and Limitations” section.

To prepare for ISSU or eFSU, perform the tasks in the following sections:

• Disabling the Compatibility Matrix Check
• Verifying the Boot Image Version and Boot Variable
• Verifying Redundancy Mode
• Verifying ISSU State

Disabling the Compatibility Matrix Check

To perform a software upgrade on the Cisco 7600 router, you must first disable the compatibility matrix check by issuing the following command in global configuration mode:

Verifying the Boot Image Version and Boot Variable

Before starting, it is a good idea to issue the show version and show bootvar commands to verify the boot image version and BOOT environment variable for the router, as shown in the following examples:

Verifying Redundancy Mode

It is also a good idea to verify that redundancy mode is enabled and that NSF and SSO are configured. The following command example shows how to verify redundancy:

Verifying ISSU State

You should also verify the ISSU state, as shown here:

Copying the New Software Image

Before starting the ISSU or eFSU process, you must copy the new software image to flash memory (disk0: and slavedisk0:) on the active and standby route processors, which are located on the Cisco 7600 supervisor engine or route switch processor.

(command output omitted)

(command output omitted)

Loading the New Software onto the Standby RP

Issue the issu loadversion command to start the upgrade process. This step reboots the standby supervisor engine or RSP and loads the new software image onto the standby’s route processor.
When the download is complete, you are prompted to issue the runversion command.

(The above line shows that the standby supervisor engine in slot 6 is rebooting. When the reboot is complete, the router loads the new image onto the standby.)

Note At this point, it is a good idea to check the status of the upgrade using the show redundancy and show issu state detail commands (see the following examples). When issu loadversion has finished, the standby RP should be loaded with the new software image and the RP should be in SSO mode. It might take several seconds for issu loadversion to complete; therefore, if you enter the show commands too soon you might not see the information you need.

Displaying Maximum Outage Time for Installed Line Cards (Optional)

Once the new software is downloaded, you can issue the show issu outage slot all command on the switch processor (SP) to display the maximum outage time for installed line cards:

Note For an ISSU upgrade, the command output displays NSF_RELOAD for MDR Mode, which indicates that the line cards will not be restarted or reloaded and maximum outage time will be 0 to 3 seconds.

Forcing a Switchover from Active to Standby

Issue the issu runversion command to force a switchover between the active and standby supervisor engines or RSPs. The standby supervisor engine or RSP, which has the new software image loaded, becomes active. The previously active supervisor engine or RSP becomes the standby and boots with the old software image (in case the software upgrade needs to be aborted and the old image restored).

(Switchover between supervisors occurs now. The previous standby becomes active and is running the new software version [c7600s72033]. The previous active, now standby, boots with the old software [oct22].)

(command output omitted, new active log)

(command output omitted)

Note At this point, the new active supervisor engine or RSP is running the new software image and the standby is running the old software image. You should verify the state of the active and standby supervisor engines or RSPs as shown in the following examples (show redundancy and show issu state detail).

Note To complete the upgrade process, issue the issu acceptversion (optional) and issu commitversion commands (as described in the following sections).

Accepting the New Software Version and Stopping the Rollback Process (Optional)

You must either accept or commit the new software image, or the rollback timer will expire and stop the upgrade process. If that occurs, the software image reverts to the previous software version. The rollback timer is a safeguard to ensure that the upgrade process does not leave the router nonoperational.

The following command sequence shows how issu acceptversion stops the rollback timer to enable you to examine the functionality of the new software image. When you are satisfied that the new image is acceptable, issue the issu commitversion command to end the upgrade process.

Now view the rollback timer to see that the rollback process has been stopped:

Committing the New Software to the Standby

Issue the issu commitversion command to load the new software image onto the standby supervisor engine or RSP and complete the software upgrade process. In the following example, the new image (c7600s72033) is loaded onto the standby supervisor engine in slot 5:

(The standby supervisor engine in slot 5 begins rebooting. It then loads the new image.)

(command output omitted)

Note The software upgrade process is now complete. Both the active and standby supervisor engines or RSPs are running the new software version.

Verifying the Software Installation

You should verify the status of the software upgrade. If the upgrade was successful, both the active and standby supervisor engines or RSPs are running the new software version.

Aborting the Upgrade Process

You can manually abort the software upgrade at any stage by issuing the issu abortversion command. The upgrade process also aborts on its own if the software detects a failure.

If you abort the process after you issue the issu loadversion command, the standby supervisor engine or RSP is reset and reloaded with the original software.

The following is an example of the issu abortversion slot image command that shows how to abort the software upgrade process:

Note Before you issue the issu abortversion command, make sure that the standby supervisor engine or RSP is Up (STANDBY HOT [in SSO] or COLD [in RPR]).